In 1975 Fred Brooks proposed that “adding manpower to a late software project makes it later.” This is now known as “Brooks’s Law.”

While Brooks’s observation was specific to late software projects, it rings true for other types of projects and where it is tempting to add personnel to a team.

Why does adding people to a team create inefficiency? There are three primary reasons:

1. Ramp-Up Time

A new person on a team isn’t instantly additive. On the contrary, a new team member often sucks time from their teammates as they need to be trained and brought up to speed. Depending on the project, it can take days, weeks, or months for the new person to be additive to the team’s productivity.

2. Communication Overhead

As more people are added to a team, communication becomes exponentially complex. For example, two people on a team yields one line of communication, while three people creates three, and four people create six, and so on. It looks like this:

Thus, as more people are added to a team, it takes more effort for everyone to be in sync with what everyone else is doing. It leads to more meetings, more emails, more checking in with each other. Technology such as CRM systems and intranets help manage this problem, but it’s tough to add a person without adding to communication overload.

3. Many Tasks Aren’t Divisible

Where tasks are divisible, adding people does speed things up. For example, if I want to plant 4 trees in my yard, adding a person to help me will halve the time needed to plant them. But in many tasks aren’t so easily divisible — an example Brooks uses is “while it takes one woman nine months to make one baby, nine women can’t make a baby in one month.” So true. More than one person at a time can’t work on a spreadsheet. It’s tough for multiple people to work on the same slides in a presentation. Etc.

Battling Brooks Law

Some things to do to mitigate Brooks’s Law include:

• It may be better to have more teams but smaller ones — where the teams work on a more focused and intense basis. Or create sub-teams where projects are divisible and have the sub-teams focus on their part.

• Train new team members in a way that they don’t negatively affect efficiency. Try training prior to them joining the team or shadowing experienced team members while they work.

• Use technology like CRM systems and intranets (like Slack or Microsoft Teams) to assist with communication to keep teams in sync.

Above all else – recognize that throwing people at a problem/project may negatively impact team efficiency and dynamics.